The solar-powered Marble Machine is a unique, laser-cut project you can build at home, combining model-building, solar-power, and cool mechanical function that people will definitely want to play with & ask about. Putting it together requires simple tools & a soldering gun. Once complete, its Solarengine circuit stores the light from the solar cell, and releases it in an occasional pulse that drives the mechanics. In sunlight, the motor drops a ball every half minute. In indoor light, motor pulses decrease to every few minutes. There’s also a hand crank to manually advance the marble wheel if you get impatient.